Scraper apron closing mechanism

ABSTRACT

An articulated scraper apron in which the apron lip is pivoted to the support arms. The apron and arms are controlled by fluid actuators such that the apron lip actuator is controlled responsive to a predetermined pressure in the support arms actuator.

United States Patent 11 1 1 11 3,739,506 Klett et al. June 19, 1973 1 SCRAPER APRON CLOSING MECHANISM 2,890,805 11/1956 Pilch 91/412 2,168, 13 8 l 3 d Inventorsl Gene 1011, 111-; 2,227,233 1/134? g Kflkaly, Phoemx, Arm; Nqrman E- 2,330,113 12/1938 Daniels 37/1310. 5 Risk, Pe ria; R g Smith, Jollet, 2,529,848 11 1950 Murray 37/126 AD 130th of [11. 2,979,215 4/1961 Brisson 37/D1G. S 3,006,088 10/1961 Layton 37/D1G. 5 Ass1gnee= Caterlllllal' Tract" C09 3,651,589 3 1972 Reynolds...... 37/126 AA 22 Filed: Nov. 8, 1971 [21] Appl- No.1 196,8 7 Primary Examiner-Robert E. Pulfrey Assistant Examiner-C. W Hanor Related U.S. Application Data I Att F 1d P l [63] Continuation of Ser. No. 831,500, June 9, 1969, omey ryer Tjensvo hll lps & Lamp) abandoned.

[52] U.S. C1. 37/126 AA, 37/126 AD, 37/DIG. 5 [57] ABSTRACT [51] Int. Cl. E021 3/75, E02f 3/87 [58] Field 01 Search 37/D1G. l, DIG. 5, An articulated scraper apron in which the apron lip 18 37/1316. 1316- 15, 126 pivoted to the support arms. The apron and arms are 126 126 AA, 4; 91/414 controlled by fluid actuators such that the apron lip actuator is controlled responsive to a predetermined pres- [5 6] Ref Clted sure in the support arms actuator.

UNITED STATES PATENTS 3,574,960 4/1969 Peterson 37/129 5 Claims, 5 Drawing Figures WWW 3.739.506

sum 1 m 4 INVENTOR'" GENE R. KLETT JOSEPH KOKALY NORMAN E. msn ROGER M. SMITH 9- f u *4 Z ATTORNEYS PAIENIED'JUIIQW 3.739.506

SHEEIZN I INVENTORS GENE R, KLETT NORMAN E. RISK BY ROGER M. SMITH KTTRNEY PATENIEU J11!" 9 3. 739 l. 506

saw u or 4 INVENTORS GENE R. iKLETT JOSEPH KOKALY NORMAN E. RISK BY RQGER M. SMITH 1 SCRAPER APRON CLOSING MECHANISM This application is a continuation of application Ser. No. 831,500 filed June 9, 1969, now abandoned.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates generally to scraper aprons and more particularly to structure for pivoting the lip portion of the apron away from the scraper cutting edge so as to produce a better approach angle relative to the material ahead of the bowl.

The inability of a scraper apron to close efficiently when handling most materials is an old and persistent problem. Even with a hydraulically actuated apron, closure is generally slow and erratic when loading some soils. In loose, granular material, the usual result of this difficulty is a substantial leakage of material out of the bowl before the apron can be fully closed. A conscientious and experienced operator can minimize this loss by frequent movements of the bowl lift and apron close controls. In many cases, however, an operator will merely raise the bowl, overrun the bulldozed pile, and then close the apron without concerning himself about the loss of a portion of the load.

In dry, granular material, little relative motion takes place between the soil and the apron surface. The material quickly fills any voids and is squeezed by attempted closure of the apron. Further closure of the apron requires very high actuating force, producing full sliding of the apron surface around the densely packed soil in the bowl. The internal closing resistance builds up very rapidly with apron movement, and the uniform consistency (lack of voids) in the soil contributes to the rapid lock up of the apron. In cohesive material having voids, greater apron closure can be effected before a very high resistance is developed.

Three of the main reasons why an apron will not close in dry, sandy or rocky material are: 1) friction resistance forces on the inside of the apron are great enough to prevent adequate closing; 2) most aprons are relatively thick and approximate box sections which compress the material ahead of them and do not effectively knife their way through the material friction forces on the outside of the apron against the bulldozed material contribute to inadequate closing and the wide box section and the friction forces on the outside of the apron are enough, by themselves, to prevent closing the apron; and, 3) a rock or other rigid object, between the apron lip and the cutting edge, prevents closing.

Loose, granular material is often lost from the scraper bowl since the material tends to spill out below the apron before it is closed, if the apron does not close fast enough. Further, if the apron comes down on a rock or similar object and cannot be closed, a great deal of such material can be lost.

Since many scrapers are often used in loose, granular, or rocky material, where apron spillage can be a significant problem, the present invention has been developed wherein means pivot the apron lip forwardly to achieve a better approach angle, allowing it to cut through the material more easily. Structure can also be provided so that the apron lip may be pivoted fore and aft to work its way through the material ahead of the cutting edge.

It is therefore an object of this invention to provide a scraper apron with an improved closing action.

It is also an object hereof to provide a scraper apron which is articulated relative to its arms.

It is also an object hereof to provide a scraper apron with means for adjusting an arcuate portion of the apron relative to the arms about a pivot connection.

It is a further object of this invention to provide a scraper apron which is articulated relative to its arms by the hydraulic system which raises and lowers the apron.

It is a still further object hereof to provide a scraper which is articulated relative to its arms by a hydraulic system which is independent of that system which raises and lowers the apron.

It is also an object hereof to provide a scraper apron which produces improved operation when handling loose, granular, or rocky material.

It is also an object hereof to provide a scraper apron wherein apron spillage of such materials is significantly reduced.

It is a further object hereof to provide a scraper apron with a means to pivot the apron lip forward so as to achieve an improved approach angle, allowing the lip to knife through the material.

It is a still further object hereof to provide a scraper apron with a means to pivot the apron lip in fore and aft motion, allowing the lip to work its way through the material ahead of the cuttingedge.

Other objects and advantages of the present invention will become apparent from the following description and claims as illustrated in the accompanying drawings which, by way of illustration show a preferred embodiment of the present invention and principles thereof and what is now considered to be the best modes contemplated for applying these principles. It is recognized that other embodiments of the invention utilizing the same or equivalent principles may be used, and structural changes may be made as desired by those skilled in the art, without departing from the present invention and purview of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a tractor-scraper combi' nation utilizing the present invention;

FIG. 2 is an enlarged view of an embodiment which may be utilized to operate the scraper as shown in FIG.

FIGS. 3 and 4 show a side elevation and a plan view respectively, of a portion of a second embodiment which may be utilized to control the scraper; and

FIG. 5 is a side elevation of a third embodiment of the scraper articulation means.

DETAILED DESCRIPTION Referring now to FIG. 1, there is shown a tractor 11 to which a scraper 13 is suitably hitched at a scraper gooseneck 15. The scraper generally comprises a bowl 17 having, at the forward end thereof, an apron gener ally illustrated at 19, which serves to close the forward end of the bowl.

Referring now to FIG. 2, a portion of the apron and its actuating structure is shown in greater detail. Side plates 21 and the arcuate portion of the apron comprise an apron closure member and are pivotally supported at 23 on a pair of arms 25 which, in turn, are pivotally supported at 27 to the scraper bowl sides 29. A pair of stop blocks 31 rigidly secured to each sidewall limits downward movement of the arms 25.

Raising of the apron is accomplished in a conventional manner by a lift cylinder 33 within the scraper gooseneck l5 and connected to the apron 19 by a lever 35 and link 37. The apron pivots about its pivot point 23 until surfaces 39 on the apron contact stops 41 on the arms which form cooperating means operatively associating the arms and apron. Further upward movement of the apron lifts the arms away from blocks 31 on the bowl sides. This provides a larger opening ahead of the cutting edge 43, positioning the bottom edge portion of the apron lip 45 at a relatively steep angle with respect to the material ahead of the bowl.

With the surfaces 39 positioned against stops 41, the apron lip 45 has a better approach angle relative to the material ahead of the bowl when the apron is lowered. This permits the apron lip to knife its way through the material. Surfaces 39 remain against stops 41 until the arms 25 contact the stop blocks 31, whereupon further powering of the apron downwardly pivots the arcuate portion about its pivot connection 23 to close the front of the bowl. A limited amount of material is swept into the bowl in this action. Further, with the arcuate portion pivoted with respect to the arms, it may seek its own way through the material ahead of the cutting edge.

Referring now to the embodiment shown in FIGS. 3 and 4, the apron, generally illustrated at 119, comprises a fabricated arcuate structure 121 which extends substantially across the full inside width of the scraper bowl. The arcuate structure is pivotally supported at 123 by a pair of arms 125. Arms 125, in turn, are pivotally secured at 127 to the scraper bowl sidewalls 129. A pair of blocks 131 rigidly secured on each of the sidewalls provides down stops for arms 125.

Arms 125 are interconnected by a torsion tube 147 extending between upper projecting brackets 149 rigidly secured to the arms. A pair of cylinders 151, pivotally secured to the arms 125 and the structure 121 at 153 and 155, respectively, pivots the apron about pivot 123 by extension and retraction of the piston within the cylinder 151 to form cooperating means operatively associating the arms and apron.

Fluid for actuation of the jacks 151 is supplied from a scraper double-pump steering circuit. The central position 157 of a three-positioned pilot operated valve 159 communicates fluid from a reservoir 161 by way of the large steering pump 163 through a steering valve 165, and to the scraper steering jacks (not shown). Shifting of valve 159 to a position 167 communicates fluid to the rod end ofjacks 151, retracting the pistons into the cylinders, and pivoting the lower lip 145 of the apron forward of the scraper cutting edge 143.

Shifting of the valve to a position 169 directs pressurized fluid to the head end of cylinders 151, extending the pistons so as to pivot the apron lip 145 rearwardly toward the cutting edge 143. With fluid being communicat'ed to the cylinders, steering of the tractor can still be accomplished by the small steering pump 17] directing fluid through steering valve 165 to the steering cylinders.

Raising and lowering of the entire apron is accomplished in a conventional manner by a link 137 pivotally secured to the front surface of the apron and to a lever 13 5. Lever 135 is raised and lowered by an apron lift cylinder (not shown) within the scraper gooseneck 115.

In operation, the scraper bowl would be loaded in a conventional manner, with the apron raised above the cutting edge, permitting the material being loaded to flow into the bowl. Once the bowl is filled and the apron is to be lowered to close the front of the scraper bowl, difficulty may be encountered due to the type of material which is being loaded and/or a rock or other rigid objects may be caught between the apron lip and the cutting edge. Utilizing a machine with this embodiment, the jacks 151 can be retracted, pivoting the apron lip 145 well ahead of cutting edge 143 so that downward movement of the apron about pivot 127 causes the apron lip to approach the material ahead of the cutting edge at a relatively steep angle. This permits the lip to more readily knife its way through the material. When the arms reach stops 131, the pistons in the cylinders 151 may then be extended, pivoting the apron lip rearwardly toward the cutting edge to the phantom line position shown in FIG. 3, closing the front of the scraper bowl.

If the above described action does not result in complete closure of the bowl, the jacks 151 can be extended and retracted by alternately shifting valve 159 from positions 167 to 169, thereby oscillating the apron through the material until the bowl is closed.

Referring to FIG. 5 there is shown a third embodi ment of the present invention wherein an apron lip section 221 is pivotally secured to the arms 225 by a plurality of hinges 223 extending across the front of the apron. Pivoting the lip is accomplished by a pair of hydraulic jacks 251 secured to the outer ends of the front surface of the arms by pivots 253 on brackets 249 projecting from the arms and to the lip section 221 by pivots 255 to form cooperating means operatively associating the arms and apron.

Retraction of the jacks 251 pivots the lip forward and away from the scraper cutting edge to a relatively steep angle with respect to the material ahead of the bowl, allowing the lip to knife its way through granular or rocky material which might otherwise cause difficulty in closing the apron.

The arms 225 may be limited in their downward movement either by stop blocks 231 or by contact with the cutting edge 243 of the bowl.

The entire apron may be raised and lowered by means ofa piston-cylinder 223 acting upon a lever 235 which is pivotally attached to the gooseneck 215 and a link 237 which is pivoted on the main arcuate portion of the apron. Retraction of the piston into the cylinder powers the apron downwardly until the resistance to closing is such that pressure in the cylinder 233 exceeds the pressure setting ofa sequence valve 261. When that pressure is exceeded, fluid is directed through a pilot operated control valve 263 and a conduit 265 to the head end of cylinder 251. This causes the apron lip 245 to commence pivoting rearwardly about its pivot at hinges 223.

Under some conditions of light resistance, the apron would be completely lowered prior to opening of sequence valve 261 so that the lip would be closed by cylinder 233.

Fluid from the rod ends of jacks 251 is returned to tank through a conduit 267, control valve 263, and conduits 269 and 271. The pressurized fluid in conduit 265 is communicated through a pilot line 273 to unseat a check valve 275 in conduit 267, thereby permitting the fluid to be returned to the tank.

As discussed relative to the previously described embodiments, it will sometimes be necessary to oscillate the apron lip fore and aft through the material ahead of the scraper cutting edge to effect closing of the scraper bowl. This may be achieved relative to this embodiment by alternately shifting control valve 263 against its biasing spring 281. When this is done, fluid is directed through the valve to the rod end of cylinder 251 via conduit 267. Fluid from the head end of the jacks is then forced back to tank through conduit 265, valve 263, and conduits 269 and 271. Pressurized fluid in conduit 267 is communicated by a pilot line 283 to act upon a check valve 285, permitting the fluid to be returned to the tank.

Raising of the apron by extension of the cylinder 233 pressurizes conduit 271, the fluid then being communicated to the head end of the jack 251. This causes the lip 245 to be pivoted away from the cutting edge 243. With the lip in this position, a steeper approach angle to the material being loaded is realized such that the lip can knife its way through the material. Pivoting of the lip forwardly also provides additional clearance through which rock and other material can be loaded and ejected. Fluid from the rod end of the jacks 251 is returned to tank by means of conduit 265, valve 263, and conduits 287, 289, 291 and 293. A check valve 295 in conduit 289 blocks communication of fluid through the line when the apron is being lowered, insuring that sequence valve 26] functions and permits free flow in the opposite direction.

The pilot operated check valves 275 and 285 block communication of fluid from the jacks 251 when there is no pressurized fluid in either conduit 271 or 293, thereby insuring that the lip cannot pivot away from the position in which the operator has placed it.

Of course, any suitable hydraulic circuit which would produce the desired result, could be substituted for that illustrated in FIG. 5.

Thus, the Applicants have described and illustrated a plurality of embodiments of a new and improved articulated scraper apron which produces a true advancement in the art in view of the greatly improved capability of scrapers utilizing such aprons. Many other embodiments and modifications of the invention, e.g., utilization of only single elements where plural have been described will be obvious to those skilled in the art which embodiments and modifications are included within the scope of the following claims.

We claim:

1. A tractor-scraper combination having a bowl comprising sidewalls, a floor connected to said sidewalls and a cutting blade secured on a forward edge of said floor, an arm pivotally mounted upon each of said sidewalls, apron means pivotally mounted upon and extending laterally between said arms for normally closing an open forward end portion of said bowl, stop means secured to at least one of said sidewalls for engaging at least one of said arms to limit the pivoting movement of said at least one arm toward said floor of said bowl, first pressure fluid actuating means connected between the tractor of said tractonscraper and at least one of said arms for selectively pivoting said arms toward and away from said filoor, second pressure fluid actuating means connected between at least one of said arms and said apron means for pivoting said apron means about said arms, and fluid communicating means for communicating fluid supply between said first and second pressure fluid actuating means, said fluid communication means controlling actuation of said second pressure fluid actuating means in response to the establishment of a first predetermined pressure in said first pressure fluid actuating means.

2. The invention of claim 1 wherein said first pressure fluid actuating means include a first hydraulic fluid cyl inder and lever and link member connecting said first cylinder to said arm and said fluid communicating means including circuit means for controlling the supply of hydraulic pressure fluid to and from said first hydraulic fluid cylinder.

3. The invention of claim 2 wherein said second pressure fluid actuating means include a second hydraulic fluid cylinder and means for connecting said second fluid cylinder between said apron means and said at least one arm, said circuit means including valve means and fluid transmission means for controlling the actuation of said second hydraulic fluid cylinder in response to pressure extant in said first hydraulic fluid cylinder.

4. The invention of claim 3 wherein said valve means include a sequence valve connected in fluid communication between said first and second hydraulic fluid cylinders, said sequence valve means for adjusting said valve to open only at a predetermined pressure to allow actuating fluid to flow to said second hydraulic fluid cylinder.

5. The invention of claim 4 wherein said valve means further include a control valve connected between said sequence valve and said second hydraulic fluid cylinder, said control valve having means for selective actuation independently of said sequence valve for communication of pressure fluid to and from said second bydraulic fluid cylinder to selectively pivot said apron means about said arms. 

1. A tractor-scraper combination having a bowl comprising sidewalls, a floor connected to said sidewalls and a cutting blade secured on a forward edge of said floor, an arm pivotally mounted upon each of said sidewalls, apron means pivotally mounted upon and extending laterally between said arms for normally closing an open forward end portion of said bowl, stop means secured to at least one of said sidewalls for engaging at least one of said arms to limit the pivoting movement of said at least one arm toward said floor of said bowl, first pressure fluid actuating means connected between the tractor of said tractor-scraper and at least one of said arms for selectively pivoting said arms toward and away from said floor, second pressure fluid actuating means connected between at least one of said arms and said apron means for pivoting said apron means about said arms, and fluid communicating means for communicating fluid supply between said first and second pressure fluid actuating means, said fluid communication means controlling actuation of said second pressure fluid actuating means in response to the establishment of a first predetermined pressure in said first pressure fluid actuating means.
 2. The invention of claim 1 wherein said first pressure fluid actuating means include a first hydraulic fluid cylinder and lever and link member connecting said first cylinder to said arm and said fluid communicating means including circuit means for controlling the supply of hydraulic pressure fluid to and from said first hydraulic fluid cylinder.
 3. The invention of claim 2 wherein said second pressure fluid actuating means include a second hydraulic fluid cylinder and means for connecting said second fluid cylinder between said apron means and said at least one arm, said circuit means including valve means and fluid transmission means for controlling the actuation of said second hydraulic fluid cylinder in response to pressure extant in said first hydraulic fluid cylinder.
 4. The invention of claim 3 wherein said valve means include a sequence valve connected in fluid communication between said first and second hydraulic fluid cylinders, said sequence valve means for adjusting said valve to open only at a predetermined pressure to allow actuating fluid to flow to said second hydraulic fluid cylinder.
 5. The invention of claim 4 wherein said valve means further include a control valve connected between said sequence valve and said second hydraulic fluid cylinder, said control valve having means for selective actuation independently of said sequence valve for communication of pressure fluid to and from said second hydraulic fluid cylinder to selectively pivot said apron means about said arms. 